We outlined a mathematical model of the so-called XML editing deltas and proposed a first study of their formal properties. We expected at least three outputs from this theoretical work: a common basis to compare performances of the various algorithms through a structural normalization of deltas, a universal and exible patch application model and a clearer separation of patch and merge engine performance from delta generation performance. This paper presents the full calculus and reports significant progresses with respect to formalizing a normalization procedure. Such method is key to defining an equivalence relation between editing scripts and eventually designing optimizers compiler back-ends, new patch specification languages and execution models.